first of all these controller are typically for 12 and 24, i am not aware of 48 volt but they may be available as well, or one of the others might be made to work
with a voltage divider on the sense line.
a typical controller does the following
three step chargeing, bulk, absorption, and float, and some have manual equalization
they have a ramp up feature which brings the alternator up online slowly
saving belt wear
they have a feature to tailor the output to the available hp you have driving it.
they have alternator temp sensors which save cooking the alternator
they have battery temp sensors, which is important to not only keep the battery from over temp but is used to calculate the specific voltage needed referenced to temperature.
they have programmable settings for all types of battery technologies,, at least the major ones.
voltage set points are programmable, as well as time functions etc.
and a bunch of other functions, all programmable
the retail cost for a 24 volt version is about 300 bucks, or so
ebay for around 200 maybe less
again i am not sure if they are available in 48 volt, but a call to the oem
tech dept might allow one to be used on a 48 volt system.
i know how it could be done, but will refrain from making a recommendation
check out the balmar products, and read their FAQ
Xantrex also markets one, that looks lot like the balmar, might even be
a rebadged balmar i dunno.
ample power makes one as well
there are a couple of manufactures in england as well.
the boating folks use these controllers alot, so check out the boating forums
if you have other questions specific to your application.
in reality, boating and offgrid have a lot in common in my opinion. the boating
guys have been at the offgrid thing a very long time, so i figure why not learn from their experience. why reinvent the wheel?
you asked why not run the alternator without the controller?
if you build such a system, you will either end up with
- a battery charging babysitters nightmare, or
- an instrument of torture for the batteries, or
- a murder weapon of the batteries, or worse yet
- a combination of the three
without some form of control with temp sensors you risk
overheating the alternator, burnout resulting with increased costs involved
without some form of control with temp senseing of the batteries
you risk damage to the batteries from overheating, under or overcharging
unless you are very attentive and careful.
one can certainly charge the batteries effectively and safely if he is careful
and monitors the process, that requires babysitting them over the complete charge
regime.
or he can use a controller, set it up correctly and not have to stand watch
i guess it all depends on how much your time is worth.
basically if i had a large set of expensive batteries that i were to depend upon
in an offgrid installation, i would step up to the use of a controller.
even if i had lots of time on my hands.. sooner or later i would be absent, sick or just make a stupid miscalculation and end up costing me more than the cost of a controller in battery or alternator damage.
let alone fuel consumption, which is also a significant factor.
the controllers are designed to charge the batteries in the most efficient manner possible, that means lower run times and less fuel burned.
then there is system life span, lower run times usually result in longer life of the components, engine and alternator.
lots of factors to consider
bob g
bob g